During sleep, a person's weight and the number of hours he/she sleeps determine how many calories are burned. Normally, a person burns about 0.42 calories for every pound in one hour of sleep. For instance, a 150 lb. person burns about 63 calories in one hour. If this person sleeps for eight hours total, he/she burns 504 calories for the whole duration. Just multiply the average rate with every pound of weight and number of hours of sleep. Therefore, the heavier a person is, as well as the longer a person sleeps, the more calories are burned